GLACIATION OF PRINCE WILLIAM SOUND 471 600 feet above another channel west of Knight Island, as well as by the submerged hanging valleys which it receives as tributaries from the eastern side of Knight Island. Of these, mention may be made of Snug Harbor, Marsha Bay, and Bay of Isles. Within the latter, are tributary coves, forming submerged hanging valleys of the second order. A third channel beneath the surface of Prince William Sound lies northwest of Knight FIG. 72. STJBMABINB TOPOGBAPHT OF PHINCH WIUIAM SOUND. Island. The southern end of it leads into a fiord called Knight Island Passage. Near the mouths of Passage Canal and of Port Nellie Juan we lack soundings, but since the junction of Passage Canal and Port Wells is over 1400 feet deep and the northern known portion of this submarine channel is 2400 feet deep, it seems likely that in the intervening seventeen miles there is either a deep channel or several deep basins between the islands.